At age 22, there was a detailed interview about use of various tobacco products, including cigarettes, cigars, pipe and smokeless tobacco. First, the respondents were asked if they had ever used those products daily or almost daily for one month. Those who replied ‘no’ to all these items were categorized as never users (245 males, 367 females). For those who had replied ‘yes’ to at least one of the items, the following question was asked: “At what age did you start using tobacco on daily basis?” Based on the responses, the ever users were categorized into two categories of regular tobacco use initiation, i.e. ‘late onset’ (14–22 years of age; 306 males, 271 females) and ‘early onset’ (<14 years of age; 43 males, 36 females). Cotinine measurements in a sample of never smokers confirmed the absence of recent tobacco use.
